package DataStuctures.PriorityQueue;

public class Array<E> {

    private E[] data;

    private int size;


    //构造函数
    public Array(int capacity){
//        data = new E[capacity];    不能这样创建数组
        data = (E[]) new Object[capacity];
        size = 0;
    }

    //无参构造函数
    public Array(){
        this(10);
    }

    public int getSize(){
        return size;
    }

    public int getCapacity(){
        return data.length;
    }

    public boolean isEmpty(){
        return size == 0;
    }

    public void addLast(E e){

        if(size == data.length)
            throw new IllegalArgumentException("AddLast failed.Array is full.");

        data[size] = e;
        size ++;
    }


    //在第index个位置插入一个元素e
    public void add(int index,E e){
        if(index < 0 || index>size )
            throw new IllegalArgumentException("Add failed.Require index >= 0 and index <= size.");

        if(size == data.length){
            resize(2 * data.length);
        }


        for (int i = size - 1; i >= index ; i--) {
            data[i + 1] = data[i];
        }

        data[index] = e;
        size ++;
    }


    //在第一个位置添加元素
    public void addFirst(E e){
        add(0,e);
    }

    public void swap(int i,int j){
        if (i < 0 || i >= size || j < 0 || j >=size) {
            throw new IllegalArgumentException("Index is illegal.");
        }

        E t = data[i];
        data[i] = data[j];
        data[j] = t;

    }


    @Override
    public String toString(){
        StringBuilder rs = new StringBuilder();
        rs.append(String.format("Array: size =%d , Capacity = %d",size,data.length));
        rs.append('[');
        for (int i = 0; i < size; i++) {
            rs.append(data[i]);
            if (i != size-1)
                rs.append(",");
        }
        rs.append(']');
        return rs.toString();
    }

    //获取index索引位置的元素
    public E get(int index){

        if(index < 0 || index >=size ){
            throw new IllegalArgumentException("Get Failed.Index is illegal.");
        }
        return data[index];
    }


    //修改index索引位置的元素为e
    void set(int index,E e){
        if(index < 0 || index >=size ){
            throw new IllegalArgumentException("Get Failed.Index is illegal.");
        }
        data[index] = e;
    }

    //查找数组是否有元素e
    public boolean contains(E e){
        for (int i = 0; i < size; i++) {
            if(data[i].equals(e)){
                return true;
            }
        }
        return false;
    }

    //查找数组中e所在的索引 如果不存在返回-1
    public int find(E e){
        for (int i = 0; i < size; i++) {
            if(data[i].equals(e)){
                return i;
            }
        }
        return -1;
    }


    //从数组中删除index位置的元素，返回删除的元素
    public E remove(int index){
        if(index < 0 || index >=size ){
            throw new IllegalArgumentException("remove Failed.Index is illegal.");
        }

        E ret = data[index];

        for (int i = index + 1; i < size; i++)
            data[i-1] = data[i];
        size --;
        data[size] = null;    //让垃圾收集器回收 loitering object != menory leak

        if(size == data.length/4 && data.length / 2 !=0)   //——>lazy remove
            resize(data.length / 2);

        return ret;
    }

    //从数组中删除第一个元素，返回删除的元素
    public E removeFirst(){
        return remove(0);
    }


    //从数组中删除最后一个元素，返回删除的元素
    public E removeLast(){
        return remove(size -1);
    }


    //重复元素没做处理[只删除一个]
    public void removeElement(E e){
        int index = find(e);
        if (index != -1) {
            remove(index);
        }
    }


    //数组扩容
    private void resize(int newCapacity) {
       E[] newData =  (E[]) new Object[newCapacity];
        for (int i = 0; i < size; i++) {
            newData[i] = data[i];
        }
        data = newData;
    }


    public E getLast(){
        // return data[size-1]   ->不a可行 少了一层判断
        return get(size -1);
    }



    public E getFirst(){
        return get(0);
    }







}
